Mechanism for driving a rotating jumping member in a timepiece

ABSTRACT

A mechanism for driving a rotating jumping member in a timepiece comprising a driving member rotating at a constant speed and coupled to the jumping member by a spring, a pallet pivoting about a fixed axis parallel to the common axis of the driving and jumping members, and a cam integral with the driving member and having a profile formed of lugs distributed at a uniform pitch about the aforesaid common axis, the jumping member having teeth which are successively blocked and then released by the pallet in the course of rotation of the jumping member.

United States Patent [191 Charbonney, deceased et al.

MECHANISM FOR DRIVING A ROTATING JUMPING MEMBER IN A TIMEPIECE Ebauches S.A., Neuchatel, Switzerland Filed: Aug. 19, 1974 Appl. N0.: 498,428

Assignee:

Foreign Application Priority Data Aug. 20, 1973 Switzerland ll958/73 US. Cl. 58/116 R, 58/125 B, 58/58 Int. CL. G04b 15/00, G04b 19/02, G04b 19/24 Field of Search 58/1 l6 R, 125 B, 58

References Cited UNITED STATES PATENTS OBrien 58/116 R l Mar. 18, 1975 2,871,702 2/1959 Tetro 58/116 X 3,427,799 2/1969 Besson 521/58 Primary Examiner-George H. Miller, Jr. Atmrney, Agent, or Firm-Stevens, Davis, Miller &

Mosher [57] ABSTRACT A mechanism for driving a rotating jumping member in a timepiece comprising a driving member rotating at a constant speed and coupled to the jumping member by a spring, a pallet pivoting about a fixed axis parallel to the common axis of the driving and jumping members, and a cam integral with the driving member and having a profile formed of lugs distributed at a uniform pitch about the aforesaid common axis, the jumping member having teeth which are successively blocked and then released by the pallet in the course of rotation of the jumping member.

13 Claims, 4 Drawing Figures PATENTEUHAR] 8 I975 sum 1 5 2 MECHANISM FOR DRIVING A ROTATING JUMPING MEMBER IN A TIMEPIECE This invention relates to a mechanism for driving a rotating jumping member in a timepiece, comprising a driving member rotating at a constant speed and coupled to the jumping member by a spring, a pallet pivoting about a fixed axis parallel to the common axis of the aforesaid members, and a cam integral with the driving member and having a profile formed of lugs distributed at a uniform pitch about the aforesaid common axis, the jumping member having teeth which are successively blocked and then released by the pallet in the course of the rotation of the jumping member.

Mechanisms of this type are used in certain calendar timepieces, but also in recent designs pertaining to socalled numerical or digital display watches, i.e., watches provided with a display mechanism which comprises indicator discs moving beneath a dial, the numbers or letters on which discs appear in apertures. In these display devices, the jumping member is generally integral with the indicator member itself.

Mechanisms of this type are likewise found in older timepieces where the display arrangement comprises hands, but with the hour-hand moving in jumps of onetwelfth of a revolution. In one example of such a mechanism, a cam is mounted coaxially with the cannonpinion bearing the minute-hand. The cannon-pj nion meshes with the minute-wheel, the pinion of which is engaged with the toothing of an hour-wheel. The hourhand is integral with a pipe which is in turn integral with a disc provided with a twelve-tooth star. A spring connects this star to the hour-wheel. Once per revolution the cam actuates a spring-click which enters the toothing of the twelve-tooth star integral with the hourhand, so that this hand is released once per hour and advances by one step, relaxing the spring which connects it to the hour-wheel.

In this known mechanism, and in others of the same type, it is necessary to provide for either a click-spring or a jumper-spring orelse other resilient means for blocking the jumping member while its driving member rotates and tenses the spring connecting it to the jumping member. Obviously, the action of these various springs burdens the mainspring of the movement, so that the amplitude of the balance varies according to whether it is almost time for the jumping member to advance by one step or whether, on the contrary, that member has just advanced. These disturbances of the running of the balance make it necessary in most cases to increase the energy reserve which the watch can contain, and they introduce the risk of irregular operation and of slowing down or even stoppingthe movement.

Mechanisms are also known which are intended to actuate an independent seconds-hand, i.e., one which beats seconds. In these mechanisms, the cam and the jumping member cooperate with a pallet having two pins. The cam is a wolf-toothed wheel of the same form as the jumping member, but with teeth slanting in the opposite direction. The slopes of two teeth of the cam push the pallet first in one direction and then in the other, so that the pin which blocks the jumping member first enters and then withdraws from toothing of that member. The profiles of the teeth and the pins are such that the pallet blocks the jumping member under the influence of the force of the coupling spring and of friction.

A mechanism of this type is relatively compact and reliable, but the friction absorbs a relatively large amount of power.

It is the object of this invention to provide a driving mechanism for a jumping member which can be utilized for the display of any unit of time-seconds, minutes, hours, tenths of hours, etc.--and the mechanical output of which is greater than that of the known mechanisms.

To this end, in the driving mechanism according to the present invention, the pallet comprises'two beaks, each provided with a locking-plane and a tip, each locking-plane cooperating with the teeth of the jumping member and each tip cooperating with the profile of the cam, and the locking-planes are so oriented that the pressure of the teeth of the jumping member upon each of these planes subjects the pallet to a torque which causes it to pivot and to press against the profile of the cam.

Two embodiments of the invention will now be described in detail, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a plan view of a first embodiment of the mechanism,

FIG. 2 is an axial section of the first embodiment, FIG. 3 is a plan view ofa second embodiment of the mechanism, and

FIG. 4 is an axial section of the second embodiment. FIGS. 1 and 2 show a mechanism intended to drive a rotating part 1 by jumps of 30 each. The rotating part l is intended to bear a disc, at the periphery of which the hours from 1 to 12 are inscribed. It takes the form of a star with six triangular teeth 2. Each of the teeth 2 has on one side a radial flank 3'and on the other side a slanting flank 4 which joins its tip to the dedendum of the radial flank 3 of the preceding tooth. As may be seen in FIG. 2, the star 1 has a central opening mounted so as to pivot freely on a cylindrical bearing surface 9 of a hub 5 provided with an axial retaining collar 6. The star 1 also comprises a circular rib 7 extending around the collar 6, intended to bear an hour-disc (not shown). Outside the rib 7 the star 1 has an opening 8 limited towards the outside by an arcuate edge and on the side towards the axis by a straight edge; the function of the opening 8 will be described further on.

A member in the form of a cam 10 is driven onto the hub 5 so as to hold the star 1 axially on the other side of the collar 6, while a third rotating member 11, having an ordinary toothing 12 at its periphery, is likewise driven onto the hub 5 so as to rest against the cam 10. In its outer face, the member 11 has an annular recess 13, rectangular in profile, which is closed off by a cover 14, the periphery of which is provided with monitoring notches 15. The cover 14 is clinched on the hub ofthe member 11. It holds in place a spring-wire 16 which is bent into an arc shape and engaged in the recess 13, and the ends 16a and 16b of which are bent up at right angles and pass through openings 17 and 18, of identical shape and size, and through the opening 8. The openings 17 and 18 are made in the bottom of the recess 13 and in the cam 10, respectively. Asthe' star I is mounted freely on the hub 5, it stays normally in a position where the opening 8 coincides exactly with the openings 17 and 18. It is in this position that the spring 16 is under the least tension. The cam 10 and the member 11 can rotate with respect to the star 1 through an angle corresponding tothe angle of aperture of the opening 8, this angle being a little less than 90 in the present case. In fact, as'will be seen when the usual operation of the mechanism is described, the rotation of the star 1 with respect to the other rotating parts of the mechanism reaches approximately 30.

Six lugs 19 are distributed at regular intervals along the periphery of the cam 10. Each lug 19 has a top or crest face 20, blanked in the shape of an arc coaxial with the mechanism described and limited by two symmetrical slopes 21 and 22 running at an incline of about 45 radii passing through the ends of the faces 20. Finally, between the inner end of each slope 21 and the inner end of the slope 22 of the next lug 19, there extend peripheral elements 23, likewise in the shape of an arc of a circle having its center on the axis of the mechanism. The thickness of the cam is approximately equal to that of the star 1, as may be seen in FIG. 2; and these two elements are situated immediately above one another, the cam 10 having an annular rib 24 formed by stamping, against which the star 1 rests in order to reduce the friction between these two elements.

The mechanism is caused to operate by an additional member consisting of a pallet 25 which pivots about a fixed stud 26. The pallet 25 comprises two arms 27 and 28 of unequal length, each ending in a beak 29, acting as a pallet-stone. These beaks 29 and 30 partially surround the assembly consisting of the member 11, the cam 10, and the star 1.

The pallet 25 is supported at a level such that plane faces 31 and 32, which constitute the stop-surfaces or locking-planes of the beaks 29 and 30, and edges 33 and34, which limit the plane faces 31 and 32 towards the inside and form the tips of the beaks 29 and 30, are situated at the level occupied by the star 1 and the cam 10. Moreover, the angles formed by the plane faces 31 and 32 with planes passing through the axis of the stud 26 and containing the edges 33 and 34 are so determined that when the point of one of the teeth 2 presses against one or the other of these stop-surfaces, it rotates the pallet 25 in a direction leading to the disengagement of the pallet 25. In other words, straight lines perpendicular to each of the locking-planes 31 and 32, with one line passing through the tip 33 and the other through the tip 34, pass to the outside of the pivoting axis of the pallet 25 in the case of the one line, and to the inside of that pivoting axis in the case of the other line. In FIG. 1, the jumping member 1 and the driving member 11 rotate clockwise. Thus the beak 29 of the pallet 25 is an entry-beak, whereas the beak 30 is an exit-beak for the operation of double disengagement effected by each lug 19 and each tooth 2 of the mechamsm.

The operation of the mechanism just described will be easily understood upon consideration of FIG. 1. In the position illustrated in that figure, one of the teeth, 2a, of the star 1 presses-against the stop-surface 31 of the pallet 25. As it tends to cause the pallet 25 to pivot clockwise, as viewed in FIG. 1, the terminal edge 34 of the stop-surface 32 is pressed against the top 20 of one of the lugs 19 of the cam 10. The star 1 is blocked, but the cam 10 is driven in rotation at a constant speed by a wheel-and-pinion engaged with the toothing 12 and rotating in a direction such that the member 11 is driven clockwise, as viewed in FIG. 1. It will be seen after a certain time, the slope 21, limiting the lug 19 at the rear, will come in contact with the edge 34.'ln the course of the rotationof the cam 10, the end 1611 of the spring 16 is pulled along by the cam 10, whereas the end 16a remains integral with the star 1. The result is that the spring 16 is gradually tensed. When the slope 21 passes under the edge 34, the pallet 25 will-start a gradual movement of rotation accompanied by a very slight displacement of the star 1. However, the stopsurface 31 will slide gradually under the tooth 2a blocked by the pallet 25 until the edge 33 comes in contact with the point of the tooth 2. At that moment, the edge 34 will not yet have arrived at the inner end of the slope 21, so that in the next instant, the star 1 will be released. It will advance clockwise, relaxing the spring 16, until the point of the tooth 2b strikes against the stop-surface 32 of the pallet 25. From then on, the star 1 will once more be immobilized, and the pallet 25 will tend to rotate counterclockwise, so that the edge 33 will come to rest against the cam 10. Owing to the symmetry of the periphery of the cam 10, the edge 33 will press against the beginning of the top face 20 of a lug 19, so that the process described above will recommence. The angle through which the star 1 rotates each time it is released is 30, hence one-twelfth of a revolution. Thus this mechanism lends itself to application in a digital-display watch comprising an hour-member jumping one-twelfth of a revolution per hour. In this case, the member 11 should rotate at a speed of one revolution every 12 hours.

The mechanism according to the second embodiment, on the other hand, would lend itself to application where the jumping indicator member integral with a star 41 would be a disc 42 (FIG. 4) bearing the units of the minutes at its periphery. The star 41 comprises five trapezoidal teeth 43. In the embodiment illustrated here, it is made in one piece with the disc 42 and is rotatingly mounted on the outer cylindrical bearing surface of an arcuate rib 44 of a cam 45, the center hole of which is driven onto a truncated portion of a toothing 46 of a pinion 47. Driven on at the end of the toothing 46 of the pinion 47 is a retaining washer 48 which holds the combined member 41, 42 axially in place. The rib 44 about which the combined member 41, 42 rotates defines an annular space in which is accommodated a spring 49 in the form of a blade, such as a balance-spring blade, the two ends 49a and 49b of which are bent back towards the outside and engaged in the opening between the two ends of the arcuate rib 44. Corresponding to this opening is a hollow 50 in the disc 42, into which the two bent ends 49a and 49b also enter. As will be seen in the drawing, the presence of this hollow 50 enables the star 41 to rotate about its axis through a limited angle, which may reach 36, with respect to the cam 45.

Along the periphery of the cam 45 are five lugs 51, each of which is defined by a top or crest surface 52 in the shape of an arc coaxial with the mechanism and by two slopes 53 and 54 on each sideof the top surface 52.

The forward slope 53 comprises a first steeply inclined portion, the radial height of which is equal to a portion of the height of the teeth 43, then it curves to join a second, less steeply inclined portion, and finally it ends in a last portion which again becomes steeper so as to reach an arcuate zone 55, the radius of which is approximately equal to that of the base of the teeth 43. Each rear slope 54 likewise comprises an inner portion substantially symmetrical to that of the slope 53, an intermediate portion likewise symmetrical to the intermediate portion of the slope 53, and an oblique outer portion joining the top surface 52.

The teeth 43 of the star 41 and the lugs 51 of the cam 45 cooperate with the ends of two arms of a pallet 56 which pivots about a fixed stud 57. Each of the arms of the pallet 56 has an edge or tip 58 and a stop-surface or locking-plane 59. As in the first embodiment, the thickness of these edges 58 and stop-surfaces 59 is greater than the combined thickness of the lugs 51 of the cam 45 and the teeth 43 of the star 41. The stud 57 is fastened on a support 60. The pallet 56 is held axially in place by a brace 61 fastened to the support 60.

FIG. 3 shows the relative positions of the pallet 56, the cam 45, and the star 41 just before the star 41 is to jump. The tooth 43a is still pressing against the stopsurface 59, which is inclined in such away the edge 58 lies against the bottom of the slope 54 of one of the lugs 51. The star 41 is therefore blocked, whereas the cam 45 integral with the pinion 47 is rotatingly driven by the toothing of a wheel 62 partially shown in FIG. 4. The spring 49 is under maximum tension, and at the moment when the edge 58 arrives on the arcuate zone 55 of the cam 45 by following the slope 54, the tooth 43a is released, so that the star 41 advances by one step, and the tooth 43b comes to strike against the stopsurface 59 of the pallet 56. It thus tends to cause the pallet 56 to pivot counterclockwise about the stud 57, and this presses the edge 58 against the end of the top surface 52 of the lug 51a. From then on, the pallet 56 is held by the lug 51a; and in the course of the rotation of the cam 45, the edge 59 will gradually follow along the entire length of this top surface 52, then that of the corresponding slope 54. When the edge 58 arrives at the lower end of the slope 54, the cam 45 will have rotated by about 36 with respect to the position corresponding to FIG. 3, so that the spring 49 will one more be tensed, and the edge 58 of the right-hand end of the pallet 56 will be ready to release the tooth 43b.

It will be realized that the mechanisms described consume very little energy. As a matter of fact, the pallet 25 or 56 is not subjected to the action of any spring since it is guided directly by the corresponding cam. On the other hand, as the spring 49 or 16 gradually stores up a certain amount of energy while it is being tensed, the rotation of the driving wheel is gradually braked, which burdens the mainspring. It will be understood, however, that there exists a sort of recuperation of this energy, at least in part, via the pallet. As a matter of fact, when the coupling spring between the star and the driving wheel is partially tensed, as is the situation in FIG. 3, the star 41 exerts a force upon the pallet; and this force is borne not only by the pivoting stud 57, but also by the cam against which the edge 58 of the pallet is pressing. Thus the cam is subjected to a force which tends to accelerate it and which, consequently, acts upon the movement in the same sense as the mainspring. The arrangement described above can be produced easily and constitutes a device which operates very reliably and always accurately, even with the manufacturing tolerances normal in mass-production. As the pallet is not actuated by the cam but is rather moved by the star which it blocks, and as the cam serves only to limit the possible displacement of the pallet, a shock from outside which is liable to cause a displacement-of the pallet will allow it to move only in the direction of engagement. It therefore follows that no shock can cause an untimely jump of the rotating jumping member.

When the pallet is guided by the cam but moved by the star, it may happen that before the precise moment of release, the star advances slowly through an angle corresponding to about one-tenth or one-twentieth of the jump. If it is desired to avoid this phenomenon, it suffices to provide for angles of draw such that the pallet presses on the same side of the cam as where the blocked tooth is situated In this case, there will be an instantaneous release of the star. As the case may be, the locking-planes of the beaks of the pallet might have curved profiles.

A further advantage of the mechanisms described is that they make it possible to set the time in either direction. Other advantages, finally, are their compact size and their reliability.

The driving mechanism of which two possible embodiments have just been described is suitable for many different applications. Thus it may serve to jump-drive houror minute-indicators as well as dayor dateindicators. It may likewise be used in chronographs, particularly for driving an hour-counter, a minutecounter, etc.

What is claimed is:

l. A mechanism for driving a rotating jumping member in a timepiece, comprising a driving member rotating at a constant speed and coupled to said jumping member by a spring, a pallet pivoting about a fixed axis parallel to the common axis of said members, and a cam integral with said driving member and having a profile formed of lugs distributed at a uniform pitch about said common axis, said jumping member having teeth which are successively blocked and then released by said pallet in the course of the rotation of said jumping member, wherein said pallet comprises two beaks, each provided with a locking-plane and a tip, each locking-plane cooperating with said teeth and each tip cooperating with said profile, and wherein said locking planes are so oriented that the pressure of said teeth upon each of said planes subjects said pallet to a torque which causes it to pivot and to press against said profile.

2. A mechanism in accordance with claim 1, wherein the profiles of said locking-planes and those of said lugs are paired in such a way that the torques exerted by said pallet on said cam partially compensate the variations in resistance due to the tensing of said spring.

3. A mechanism in accordance with claim 1, wherein said two beaks comprise an entry-beak and an exitbeak, and wherein said locking-planes are so oriented that a line drawn perpendicular to the locking-plane of said entry-beak through the tip of said entry-beak passes to the outside of said fixed axis, and a line drawn perpendicular to the locking-plane of said exit-beak through the tip of said exit-beak passes to the inside of said fixed axis.

4. A mechanism in accordance with claim 1, wherein said jumping member is freely engaged on a cylindrical bearing surface integral with said cam and is held axially in place by said cam on one side and by a shoulder integral with said cam on the other side.

5. A mechanism in accordance with claim 4, wherein said spring is situated in a recess in said cam.

6. A mechanism in accordance with claim 4, further comprising a tubular hub onto which said cam is driven.

7. A mechanism in accordance with claim 6, wherein said shoulder is formed by a collar made inone piece with said tubular 'hub.

8. A mechanism in accordance with claim 6, wherein said shoulder is formed by a washer fixed to said hub by. riveting from the outside or the inside.

9. A mechanism in accordance with claim 6, wherein said spring is situated in recess insaid driving member. 10. A- mechanism in accordance with claim 1, wherein the orientation of said locking-planes is such that said teeth cause said pallet to pivot in the direction of disengagement and press the one of said two beaks which is not then in contact with said jumping member against said profile.

11. A mechanism in accordance with claim 10,

, tween said camand said jumping member is'equal to wherein the number of saidlugs is equal to the number of said teeth, and'the' maximum angular clearance/behalf the pitch of the toothing of said jumping member.

12. A mechanism in accordance with claim 11, 

1. A mechanism for driving a rotating jumping member in a timepiece, comprising a driving member rotating at a constant speed and coupled to said jumping member by a spring, a pallet pivoting about a fixed axis parallel to the common axis of said members, and a cam integral with said driving member and having a profile formed of lugs distributed at a uniform pitch about said common axis, said jumping member having teeth which are successively blocked and then released by said pallet in the course of the rotation of said jumping member, wherein said pallet comprises two beaks, each provided with a locking-plane and a tip, each locking-plane cooperating with said teeth and each tip cooperating with said profile, and wherein said locking planes are so oriented that the pressure of said teeth upon each of said planes subjects said pallet to a torque which causes it to pivot and to press against said profile.
 2. A mechanism in accordance with claim 1, wherein the profiles of said locking-planes and those of said lugs are paired in such a way that the torques exerted by said pallet on said cam partially compensate the variations in resistance due to the tensing of said spring.
 3. A mechanism in accordance with claim 1, wherein said two beaks comprise an entry-beak and an exit-beak, and wherein said locking-planes are so oriented that a line drawn perpendicular to the locking-plane of said entry-beak through the tip of said entry-beak passes to the outside of said fixed axis, and a line drawn perpendicular to the locking-plane of said exit-beak through the tip of said exit-beak passes to the inside of said fixed axis.
 4. A mechanism in accordance with claim 1, wherein said jumping member is freely engaged on a cylindrical bearing surface integral with said cam and is held axially in place by said cam on one side and by a shoulder integral with said cam on the other side.
 5. A mechanism in accordance with claim 4, wherein said spring is situated in a recess in said cam.
 6. A mechanism in accordance with claim 4, further comprising a tubular hub onto which said cam is driven.
 7. A mechanism in accordance with claim 6, wherein said shoulder is formed by a collar made in one piece with said tubular hub.
 8. A mechanism in accordance with claim 6, wherein said shoulder is formed by a washer fixed to said hub by riveting from the outside or the inside.
 9. A mechanism in accordance with claim 6, wherein said spring is situated in recess in said driving member.
 10. A mechanism in accordance with claim 1, wherein the orientation of said locking-planes is such that said teeth cause said pallet to pivot in the direction of disengagement and press the one of said two beaks which is not then in contact with said jumping member against said profile.
 11. A mechanism in accordance with claim 10, wherein the number of said lugs is equal to the number of said teeth, and the maximum angular clearance between said cam and said jumping member is equal to half the pitch of the toothing of said jumping member.
 12. A mechanism in accordance with claim 11, wherein each said lug comprises a crest in the shape of an arc of a circle concentric with said cam, a rear flank intended to retain said tips of said two beaks, and a forward flank having contour similar to that of said rear flank.
 13. A mechanism in accordance with claim 12, wherein said rear and forward flanks each comprise two end portions more steeply inclined than the intermediate portion joining them. 